Noncontrolling Interest - Operating Partnership/Limited Partners' Equity - Preferred Units (Details) (USD $)									12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Series I-2 [Member]	Dec. 31, 2010 Series I-2 [Member]	Dec. 31, 2011 Liberty Property Limited Partnership [Member]	Dec. 31, 2010 Liberty Property Limited Partnership [Member]	Dec. 31, 2011 Liberty Property Limited Partnership [Member] Series I-2 [Member]	Dec. 31, 2010 Liberty Property Limited Partnership [Member] Series I-2 [Member]	Dec. 31, 2011 Unredeemed [Member] Series I-2 [Member]	Dec. 31, 2011 Redeemed [Member] Series I-1 [Member]
Preferred Units [Line Items]
Preferred Units, Annual Cash Distributions									$ 57,000
Noncontrolling Interest in Operating Partnerships									$ 7,537,000
Preferred Units, Outstanding	9,740,000	9,740,000	301,483	0	9,740,000	9,740,000	301,483	0	301,000
Redeemable Preferred Units Liquidation Preference									$ 25
Preferred Stock Dividends Rate Percentage Or Per Dollar Amount									6.25%
Preferred Units, Issued										362,369
Preferred Stock, Value, Issued										$ 9,100,000
Preferred units, Redeemed										362,369